K143094 · Semler Scientific, Inc. · JOM · Mar 5, 2015 · Cardiovascular
Device Facts
Record ID
K143094
Device Name
QuantaFlo
Applicant
Semler Scientific, Inc.
Product Code
JOM · Cardiovascular
Decision Date
Mar 5, 2015
Decision
SESE
Submission Type
Traditional
Regulation
21 CFR 870.2780
Device Class
Class 2
Indications for Use
QuantaFlo is intended to aid clinicians in the diagnosis and monitoring of Peripheral Arterial Disease. It provides bilateral, non-invasive physiologic studies of the upper and lower extremity arteries, using volume plethysmography of the posterior tibial and anterior tibial/dorsalis pedis arterial distributions. Additionally, QuantaFlo may be used to perform bilateral, non-invasive physiologic studies of the upper and lower extremity arteries with provocative functional maneuvers. The device is for adult use and not for pediatric or fetal use.
Device Story
QuantaFlo aids clinicians in diagnosing Peripheral Arterial Disease (PAD). Device uses sensors with transducers to measure blood volume changes via volume plethysmography in brachial, posterior tibial, and anterior tibial/dorsalis pedis arterial distributions. Signals are digitized and processed by proprietary software on a computer to calculate a PAD-predictive result. System displays and prints waveforms and results for clinician review. Used in clinical settings by healthcare providers to assess arterial flow obstruction. Benefits include non-invasive, physiologic assessment of arterial health to inform clinical decision-making.
Clinical Evidence
Clinical performance assessed against pressure cuff/Doppler probe ABI method, with Duplex ultrasound/angiography as reference standard. Study across six sites (n=333 limbs) showed QuantaFlo 80.2% accurate vs. Doppler ABI 79.3% accurate (n=328 limbs).
Technological Characteristics
Volume plethysmography; non-invasive brief-contact sensors; PC-based software; SELV low voltage interface; plastic insulation for patient applied parts. Complies with IEC 60601-1-2 (EMC) and ISO 10993 (biocompatibility).
Indications for Use
Indicated for adult patients requiring diagnosis and monitoring of Peripheral Arterial Disease (PAD) via bilateral, non-invasive physiologic studies of upper and lower extremity arteries. Contraindicated for pediatric or fetal use.
Regulatory Classification
Identification
A hydraulic, pneumatic, or photoelectric plethysmograph is a device used to estimate blood flow in a region of the body using hydraulic, pneumatic, or photoelectric measurement techniques.
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Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002
March 5, 2015
Semler Scientific, Inc. Bob McRae Chief Operating Officer 2330 NW Everett Street Portland, Oregon 97210
Re: K143094 Trade/Device Name: QuantaFlo Regulation Number: 21 CFR 870.2780 Regulation Name: Hydraulic, Pneumatic, or Photoelectric Plethysmographs Regulatory Class: Class II Product Code: JOM Dated: January 23, 2015 Received: January 29, 2015
Dear Bob McRae,
We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food. Drug. and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.
Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting (reporting of medical devicerelated adverse events) (21 CFR 803); good manufacturing practice requirements as set forth in
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the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address
http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to
http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/default.htm for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.
You may obtain other general information on your responsibilities under the Act from the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address
http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm.
Sincerely yours,
Melissa A. Torres -S
For Bram D. Zuckerman, M.D. Director Division of Cardiovascular Devices Office of Device Evaluation Center for Devices and Radiological Health
Enclosure
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### Indications for Use
510(k) Number (if known) K143094
Device Name QuantaFlo
Indications for Use (Describe)
QuantaFlo is intended to aid clinicians in the diagnosis and monitoring of Peripheral Arterial Disease. It provides bilateral, non-invasive physiologic studies of the upper and lower extremity arteries, using volume plethysmography of the posterior tibial and anterior tibial/dorsalis pedis arterial distributions. Additionally, QuantaFlo may be used to perform bilateral, non-invasive physiologic studies of the upper and lower extremity arteries with provocative functional maneuvers.
The device is for adult use and not for pediatric or fetal use.
| Type of Use (Select one or both, as applicable) | |
|------------------------------------------------------------------------------------|-----------------------------------------------|
| <span style="font-size:16px">☑</span> Prescription Use (Part 21 CFR 801 Subpart D) | ☐ Over-The-Counter Use (21 CFR 801 Subpart C) |
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### 510(k) Summary
This 510(k) summary is being submitted in accordance with the requirements of 21 CFR 807.92.
## Submitter
| Company Name: | Semler Scientific, Inc. |
|----------------------|---------------------------------------|
| Address: | 2330 NW Everett St, Portland OR 97210 |
| Phone: | 877-774-4211 |
| Fax: | 800-303-7259 |
| Contact: | Bob McRae, Chief Operating Officer |
| Date of Preparation: | February 23, 2015 |
### Device
| Name of Device: | QuantaFlo™ |
|-----------------------|-----------------------------------------------------------------------------|
| Common or Usual Name: | Plethysmograph |
| Classification Name: | Hydraulic, pneumatic, or photoelectric plethysmographs<br>(21 CFR 870.2780) |
| Regulatory Class: | II |
| Product Code: | JOM |
### Predicate Device FloChec® (K093192)
FloChec® (K093192)
# Device Description
QuantaFlo aids clinicians in the diagnosis of vascular disease by measuring blood volume changes using volume plethysmography in the Brachial, Posterior Tibial, and Anterior Tibial/Dorsal Pedis arterial distributions. From these signals it calculates a result that is predictive of Peripheral Arterial Disease (PAD). In addition. QuantaFlo provides hard-copy waveforms as part of the report, which may be viewed on the system display, printed, and/or saved.
The clinician places a sensor and makes a measurement on each upper extremity and each lower extremity. The sensor includes a transducer, which detects changes in arterial blood volume. This signal is digitized and sent to a computer, which runs a specifically-designed software application. The application calculates the result via a proprietary algorithm, which is based on the features of the volume plethysmography signals from the Brachial. Anterior Tibial / Dorsalis Pedis, and Posterior Tibial arterial distributions.
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## Indications for Use
QuantaFlo is intended to aid clinicians in the diagnosis and monitoring of Peripheral Arterial Disease. It provides bilateral, non-invasive physiologic studies of the upper and lower extremity arteries, using volume plethysmography of the posterior tibial and anterior tibial/dorsalis pedis arterial distributions. Additionally, QuantaFlo may be used to perform bilateral, non-invasive physiologic studies of the upper and lower extremity arteries with provocative functional maneuvers.
The device is for adult use and not for pediatric or fetal use.
# Technological Comparison to Predicates
QuantaFlo uses the same technology as the predicate device. That is, it uses Volume Plethysmography of the same arterial distributions, digitizes that signal, and processes those signals via a specially-designed algorithm to calculate a result. Each device uses use a transducer, which makes non-invasive measurements with brief-contact sensors. QuantaFlo, like the predicate is a software-based device, which runs on a computer. The QuantaFlo sensor is the same as the predicate, but includes a clamshell to house the electronics.
## Performance Data
The following performance data were provided in support of the substantial equivalence determination.
### Biocompatibility Testing
The biocompatibility evaluation for the QuantaFlo device was conducted in accordance with ISO-10993. The battery of testing included the following tests:
- Cytotoxicity
- Sensitization ●
- Irritation .
### Electrical Safety and Electromagnetic Compatibility (EMC)
Electrical EMC testing was conducted on the QuantaFlo device, consisting of the PC and Sensor. The system complies with the IEC 60601-1-2 standard for EMC. Additionally, an electrical safety analysis was conducted on the QuantaFlo device. While the QuantaFlo System has Patient Applied Parts, all conductive parts are insulated by plastic material with adequate dielectric strength to withstand the 3,500VAC test potential. All electronics are powered via a SELV safe low voltage interface.
### Software Verification and Validation Testing
Software validation included application stability testing under load, USB sensor connection cycle testing, standard use-case testing, and automated use / "stress" testing. Product validation involved simulated use testing. The Level of Concern of QuantaFlo is considered a Moderate Level of Concern because it could: ... lead to an erroneous
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diagnosis or a delay in delivery of appropriate medical care that would likely lead to Minor Injury.
### Design Verification & Product Validation Testing
Product testing was completed and met all of the acceptance criteria. Verification testing involved several tests such as: dimensional verification, signal quality measurements, temperature stability testing, accelerated life testing, tensile testing of the cable to the sensor body, and electrical EMC testing. All necessary verification and validation testing has been performed for the QuantaFlo to assure substantial equivalence to the predicate devices.
#### Clinical Performance Data
The clinical performance of the QuantaFlo was assessed compared to the pressure cuff / Doppler probe ABI method, using Duplex ultrasound and/or angiography as the reference standard. Thus, using the reference diagnostic standard, the clinical accuracy of each technology was compared. Among six clinical sites, QuantaFlo was 80.2% accurate (n=333 limbs) and Doppler ABI was 79.3% accurate (328) limbs. Doppler ABI is an accepted standard for aiding in the diagnosis of PAD . The submitted study demonstrates QuantaFlo's substantially equivalent accuracy in determining the presence of PAD.
#### Conclusions
QuantaFlo shares many of the technological features as the predicate. Any differences either have no effect on safety or efficacy, or have been performance tested, assuring substantially equivalence. Further, clinical data has demonstrated efficacy in the detection of clinically significant flow obstruction.
<sup>1</sup> Rooke TW, et al, "2011 ACCF/AHA focused update of the guideline for the management of patients with peripheral artery disease (updating the 2005 guideline): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines." J Am Coll Cardiol 2011;58:2020-45.
Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.